Virginia Department of Conservation & Recreation Virginia Dam Safety & Floodplain Programs William G. Browning, Director Dam Safety & Floodplain Management

Dam Safety & Floodplain Organization Department reorganization effective November 1, 2003 Merged Dam Safety and Floodplain Management Programs Purpose is to reduce risks and hazards to the Commonwealth from dam failure and floods.

Dam Safety & Floodplain Organization

Dam Safety Program

Virginia Dam Safety Act of 1982; Amended July 1, 2002 Provides for the proper and safe design, construction, operation and maintenance of impounding structures to protect public safety. No impounding structure can ever be completely fail-safe, because of  incomplete understanding of/or uncertainties associated with natural and man-made destructive forces  material behavior and responses to those forces  quality control during construction

Code of Virginia Requirements: The law regulates impounding structures including dams used to retain or store waters or other materials. With a few exceptions, the following structures are regulated: > Impounding structures 25 feet or higher with a maximum impoundment capacity of 15 acre-feet or more > Impounding structures 6 feet or higher with a maximum impoundment capacity of 50 acre-feet or more

Definitions: Dam height is the vertical distance from the streambed at the downstream toe to the top of the dam. Maximum Impounding Capacity of a dam is the volume capable of being impounded at the top of the dam. Acre-foot is a volume of one foot of depth over one acre of area 50 acre-feet 6’-25’ high 15 acre-feet 25’ or higher

Classifying Regulated Dams Impounding structures are classified by hazard potential and size Hazard potential relates to downstream losses that may occur if the dam fails

Classes of Hazard Potential If Structure Fails Class I Probable loss of life Excessive economic loss IIPossible loss of life Appreciable economic loss IIINo loss of life expected Minimal economic loss IVNo loss of life expected No economic loss to others

Performance Standards Required for Impoundments* The required spillway design flood is based on the combination of : hazard classification size classification * 4 VAC

Spillway Functions Prevents dam overtopping Prevents erosion at base of dam

Classifications of Dams ClassDam SizeSpillway Design Flood I Large Medium Small Probable Maximum Flood (PMF) PMF ½ PMF to PMF II Large Medium Small PMF ½ PMF to PMF 100 Year to ½ PMF III Large Medium Small PMF 100 Year to ½ PMF 50 Year to 100 Year IV Small50 Year to 100 Year

What are the Responsibilities of Dam Owners?

Documents Required For Certification: Operation and Maintenance Application – I, II & III Emergency Action Plan - I, II & III Re-inspection Report – I & II Inventory Report – III & IV Note: Class IV inventory report can be completed by owner

Frequency of Submittal ClassPlan and Report Schedule I Operation and Maintenance Plan – 6 year interval Re-inspection report - 2 year interval II Operation and Maintenance Plan – 6 year interval Re-inspection Report – 3 year interval III Operation and Maintenance Plan – 6 year interval Inventory report – 6 year interval IV Inventory report - 6 year interval.

In addition… Owners of Class I, II, III and IV structures shall perform an annual owner’s inspection and submit the report in years when a professional re- inspection is not required.

Upon Submission of Forms… Dam Safety Regional Engineers: Review submitted materials May inspect structure Make recommendations to the Soil and Water Conservation Board

The Soil and Water Conservation Board Issues: Regular Operation And Maintenance Certificates Conditional Operation And Maintenance Certificates Construction Permits for new dams Alteration Permits to repair and/or upgrade dams Transfer of Ownership

Regional Engineers Also … Review new construction and alteration applications Advocate dam safety to local governments Respond to emergencies Provide training

Number Of Impoundments In Database ConditionalRegularBeing Built Total Regulated Non- Regulated* Total I II III IV *May need permitting based on regulation criteria change July 1, 2002

Types of Non-Regulated Dams Certification Type IIIIIIIVTotal Agricultural Exemption Federal License Mining Exemption Size Exemption

Why Does Dam Safety & Floodplain Management Matter? At least 18 declared flood or hurricane disasters since Hurricane Camille in 1969 Timberlake dam failure killed 2 people Flooding is the most costly and frequent Virginia natural hazard

Hurricane Floyd – September dam failures in eastern Virginia Devastated Southampton County and Franklin Floodwaters did not receed for 11 days

How Do We Prevent Damage From Floods and Hurricanes? Through Proper Dam Maintenance Build At or Above The Base Flood Elevation Elevate, Relocate or Demolish Flood-prone Structures Conserve Floodplains for Habitat, Open Space, Flood Capacity and Storage

Dam Safety & Floodplain Management Programs Need Your Help…

Please Contact Us Regarding Use of Downstream Inundation Zones Training In Floodplain Management & Dam Safety Floodplain Ordinance Review Technical Assistance For Dams & Floodplain Construction Floodplain Management Community Assistance Visit Dams 6 Feet or Higher That Are Not Properly Maintained

Contact Information Department of Conservation & Recreation Dam Safety and Floodplain Management Programs 203 Governor Street, Suite 206 Richmond, VA